Network services are widely deployed and essential in many networks. In many cases, services are provided by chains of independent service functions that follow an ordered sequence of execution. The services provide a range of functions such as security, wide area network (WAN) acceleration, firewall services, and server load balancing. Service functions that form part of the overall service may be physically located at different points in the network infrastructure, such as the wide area network, data center, campus, and so forth.
Current network service deployment models are relatively static, and bound to topology for insertion and policy selection. Furthermore, they do not adapt well to elastic service environments enabled by virtualization. New data center network and cloud architectures require more flexible network service deployment models.